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Abstract
Visual problems involved in the operation of display units have been investigated in several studies (Höller et al. 1975, Läubli et al. 1980). The results of these studies indicate mainly that visual tasks using VDU terminals may induce temporary effects in the visual accommodation system. There are, however, suggestions that visual impairment of the task depends, among other factors, particularly on workstation lighting and screen quality (Östberg 1978, Läubli et al. 1980).
In the present pilot study an attempt was made to investigate possible relations between (i) operators' accommodation changes after six hours work at a display unit and (ii) work-station lighting and screen characteristics. The measurements were carried out in two separate field studies at a Telecom Directory Enquiry Center. Operator's visual accommodation before and after work, workplace lighting, luminance contrasts and screen qualities of 29 display screen operators were measured during day and night shifts. Field laser optometry was used for determining the state of visual accommodation. Photometric and radiometric characteristics of the display screens were measured using an EG & G spectrometer-photometer.
The study revealed a low significant relationship between lighting conditions on the one side and incidence of accommodation changes on the other. More operators showed over-accommodation when working at workplaces with higher luminance contrast. The influence of screen characteristics, such as screen illuminance, luminance and irradiance upon visual accommodation were evident during the night shift.